//不要给我WA WA 叫
//一定AC
#include <iostream>
#include <cstdio>
#include <algorithm>
#include <set>
#include <map>
#include <cstring>
#include <cmath>
#include <string>
#include <unordered_map>
#include <unordered_set>
#include <vector>
#include <iomanip>
#include <climits>
#define int long long 
#define x first 
#define y second 
using namespace std;
const int N = 1e5 + 10;
int a[N];
void solve()
{
    int a,b,n;
    cin >> a >> b >> n;
    int week = 5 * a + 2 * b;
    int k = n % week;
    int day = 0;
    if(k <= 5 * a) day = ceil(k * 1.0 / a);
    else  
    {
        day = 5 + ceil((k - 5 * a) * 1.0 / b);
    }  
    int ans = (n / week) * 7 + day;
    cout << ans << endl;
}
signed main()
{
    ios::sync_with_stdio(false);
    cin.tie(nullptr),cout.tie(nullptr);
    int t = 1;
    while(t -- )  solve();
    return 0;
}
